This invention relates generally to a method for purification of crude glycerol, especially crude glycerol derived from biodiesel production using homogeneous alkaline catalysts.
High fuel prices and environmental concerns are driving development of alternative fuels, especially those derived from renewable resources. One such fuel, commonly known as “biodiesel” fuel, commonly contains methyl esters of fatty acids, and is burned in diesel engines. One source of biodiesel fuel is transesterification of triglycerides, such as vegetable oils with alcohols, typically with methanol and an alkaline catalyst. Glycerol is produced as a byproduct of this process, and typically is contaminated with salts of fatty acids and inorganic salts, including residual alkaline catalysts. The prior art discloses methods purification of glycerol, e.g., in I. Miesiac, Przemysl Chemiczny, vol. 82, pp. 1045-47 (2003). However, poor separation is achieved by prior art methods.
The problem addressed by this invention is to find an improved method for purification of crude glycerol contaminated with residual alkaline catalysts.